On the Uncertainties in the Properties of Quasar Host Galaxies
Abstract
Recent independent imaging surveys of the hosts of radio-loud quasars have not been in agreement over the resemblance between radio-loud quasar hosts and bright radio galaxies. Some authors claim that the mean absolute magnitude of radio-loud quasar host galaxies is up to a magnitude brighter than the mean magnitude of bright radio galaxies, while other authors claim that they are identical. These studies are an important test of "Grand Unified Schemes" for active galactic nuclei (AGN), which predict that the orientation-independent properties of radio-loud quasars (such as host morphology) should match those of bright radio galaxies. The lack of agreement between the recent optical imaging surveys is therefore very disturbing. We present Monte Carlo simulations that quantify the errors inherent in measuring the absolute magnitudes and morphologies of quasar host galaxies. The sizes of these errors are shown to be too small to account for the discrepant results in the literature. We therefore suggest that a serious systematic effect may be unaccounted for in at least some of the surveys and present one possible candidate. If confirmed, these results would imply that the hosts of radio-loud quasars are substantially more luminous than those of bright radio galaxies, in disagreement with the predictions of Grand Unified Schemes for AGN.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 1992
- DOI:
- 10.1086/172079
- Bibcode:
- 1992ApJ...401..474A
- Keywords:
-
- Active Galactic Nuclei;
- Galactic Structure;
- Quasars;
- Radio Galaxies;
- Astronomical Models;
- Computational Astrophysics;
- Grand Unified Theory;
- Luminosity;
- Magnitude;
- Monte Carlo Method;
- Astrophysics;
- GALAXIES: FUNDAMENTAL PARAMETERS;
- GALAXIES: QUASARS: GENERAL